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Comment by leftyted | Hacker News Reader

It only works in Chrome, which is a pretty big issue.

Per wikipedia [0], other browsers rejected PNaCL because they don't like the idea of web apps running binaries as that represents a black box for most users. In comparison, wasm is "more open". Wasm code has a human-readable text equivalent (although, frankly, the number of people who will be able to make sense of it is not high and doesn't include me).

[0] https://en.wikipedia.org/wiki/Google_Native_Client#Detractor...

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(P)NaCl was also essentially defined by Chromium's implementation, so difficult to reproduce from scratch; and tightly intertwined with the surrounding Chromium codebase, so that implementation was difficult to port to other browsers. Its success depended on a total Chromium monoculture.

Another problem was compile times - getting an efficient emit and compile time for LLVM IR was difficult and involved having to heavily optimize/replace lots of parts of LLVM's pipeline that were never designed for turbo speed because it wasn't a priority.

On the note of webassembly's text format (WAT), it's a fantastic introduction into a low level assembly. Wasm is a virtual stack machine, and it's strongly statically typed, so WAT is surprisingly readable. That being said, if the WAT you're reading wasn't hand-written, it's probably going to be unreadable anyway.

Here's an example of some mutex operations in WAT: https://gist.github.com/devsnek/9274f1420b7641d1b6c34141921f...

The livestreaming site twitch.tv uses wasm for their player, so you download a fifty something blob which is not too open I feel. I tried to have a look at it in wat and it was sadly pretty hard to figure out what was going on.

What will it take to get WebAssembly performance more in line?

I don't have a good overview but the last time I saw wasm-generated assembly it (e.g. firefox's compiler) was very very bad at actually using x86 addressing modes and other peephole-like "optimization" leading to high instruction counts and code size.

This is something that will easily improve over time without a ton of work.

Machine code can be disassembled to text form. What's different?

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